Geomorphologic controls on the age of particulate organic carbon from small mountainous and upland rivers
Article first published online: 9 SEP 2006
Copyright 2006 by the American Geophysical Union.
Global Biogeochemical Cycles
Volume 20, Issue 3, September 2006
How to Cite
2006), Geomorphologic controls on the age of particulate organic carbon from small mountainous and upland rivers, Global Biogeochem. Cycles, 20, GB3022, doi:10.1029/2005GB002677., , and (
- Issue published online: 9 SEP 2006
- Article first published online: 9 SEP 2006
- Manuscript Accepted: 24 MAY 2006
- Manuscript Revised: 16 MAY 2006
- Manuscript Received: 20 DEC 2005
- kerogen recycling;
- particulate organic carbon
 To assess the role that erosion processes play in governing the character of particulate organic carbon (POC) discharged from small mountainous and upland rivers, a suite of watersheds from Oregon, California, and New Zealand was investigated. The rivers share similar geology, tectonic setting, and climate, but have sediment yields that range over 3 orders of magnitude. The 14C age of the POC loads is highly correlated with sediment yield. Carbon isotope mass balances reveal that the rivers carry bimodal mixtures of modern-plant- and ancient-rock-derived OC. At lower yields, modern plant OC dominates the material delivered to the river by sheetwash and shallow landsliding. With increasing yield, a progressively larger part of the POC is contributed directly from bedrock erosion via deep gully incision. Our results support the inference that active margin watersheds are important sources of aged POC to the ocean.